tbuckley/cabot-search huggingface dataset:
Abstract P3016: Role Of AMPK/Sirtuin3 Signaling In HFpEF-associated Atrial Myopathy
Authors: Dan Tong, Gabriele G Schiattarella, Nan Jiang, Daniel Daou, Yuxuan Luo, Mark S Link, Sergio Lavandero, Thomas G Gillette, Joseph A Hill
Journal: Circulation Research (2022)

Background: Patients with heart failure with preserved ejection fraction (HFpEF) are uniquely predisposed to atrial fibrillation (AF), which significantly worsens clinical outcomes. Pathological atrial remodeling, i.e. atrial myopathy, usually precedes clinical AF and is deemed to be an underlying cause of AF. However, little is known about its molecular features, and no effective treatments have been identified. Method: Wild type C57Bl6 mice were fed a high fat diet (HFD) and received L-NAME via drinking water (5-8 weeks). Atrial morphology and function were assessed by echocardiography. AF was induced by transesophageal pacing. Results: We discovered that HFpEF mice manifest prominent sinoatrial node (SAN) dysfunction and are highly susceptible to pacing-induced AF, suggesting that this is an ideal model for studying HFpEF-associated atrial changes. Our findings revealed that atrial hypertrophy, contractile dysfunction, and conduction abnormalities are key features of HFpEF-associated atrial myopathy. Interestingly, we did not observe significant atrial fibrosis in this model, a prominent feature of other AF models. Importantly, we discovered impaired AMPK/Sirt3 signaling in the atria of HFpEF mice, and similar atrial defects were observed in mice with cardiomyocyte-specific loss of sirtuin3 (Sirt3) or AMPK, indicating a critical role of AMPK/Sirt3 signaling in HFpEF-associated atrial myopathy. Lastly, we found that metformin, a widely used clinical AMPK agonist, significantly attenuated AF inducibility and SAN dysfunction in HFpEF mice. Conclusion: Our “two-hit” HFpEF model successfully recapitulates HFpEF-associated atrial phenotypes. Using this model, we unveiled molecular features of a distinct atrial myopathy. We identified a critical role of AMPK/Sirt3 signaling in HFpEF-associated atrial remodeling and demonstrated the therapeutic effect of metformin. As next steps, confirming this benefit in a clinical trial is warranted.
Abstract P2087: ERBB4-Selective And Sustained Activation By NRG1 Attenuates Atrial Fibrosis And Fibrillation
Authors: Jens Van fraeyenhove, Michiel Tubeeckx, Eline Feyen, Tine Bruyns, Guido De Meyer, Samuel Murphy, Hein Heidbuchel, Vincent Segers, Gilles De Keulenaer
Journal: Circulation Research (2022)

Introduction: Atrial fibrillation (AF) results from electrical and structural remodeling of the atria, in which inflammation and fibrosis play an important role. Current therapy is limited to antiarrhythmic drugs and ablations, but does not target the structural problem. Recent studies showed that neuregulin-1 (NRG1), an epidermal growth factor family member, has anti-fibrotic and anti-inflammatory effects in the myocardium. Purpose: To test the effects of JK07, a NRG1 antibody fusion comprising an ERBB3 antagonistic antibody which selectively signals through ERBB4 preferentially over ERBB3, on atrial fibrosis and AF inducibility. Methods: Atrial samples were harvested from male rats (Wistar Han, 10 weeks old), cut into small pieces (1-2mm 2 ) and kept in low serum medium in the presence or absence of JK07 (5nM). Col1a1 and Col3a1 mRNA was quantified after 24-72 hours. AF inducibility was tested in a first AF model in which male mice (C57BL/6N, 12-15 weeks old) were treated with angiotensin-II (Ang-II, 4 weeks, osmotic mini-pumps, 3000 ng/kg/min), and in a second AF model in which mice were fed with a high fat diet (HFD, 8 weeks, 60% Kcal fat) inducing severe weight gain (56±3% increase compared to 23±4% with regular chow). In both models, AF inducibility was tested by 5 runs of programmed electrical stimulation (PES) with a trans-jugular octapolar catheter. AF inducibility (% mice inducible by ≥3 PES-runs) and duration of PES-induced AF (AF duration) were recorded. Mice were randomized for treatment with vehicle or JK07 (2x/week, 1mg/kg, IV, n=5-7/group). Results: In cultured atrial samples, Col1a1 and Col3a1 mRNA expression gradually increased up to 2-3 fold over 3 days. JK07 robustly attenuated this effect by 59±17% (p&lt;0.05). In mice, both Ang-II and HFD significantly increased AF inducibility and AF duration. In Ang-II mice, JK07 attenuated AF inducibility (from 57% to 20%) and AF duration (from 33.3 ± 15.1 to 1.5 ± 1s). In HFD mice, JK07 significantly attenuated AF inducibility (from 57% to 0%) and AF duration (from 10.9±3.2s to 0.76±0.5s, p&lt;0.05). Conclusions: These results show anti-fibrotic effects by selective ERBB4 stimulation with JK07 in atrial tissue in vitro, together with AF-preventive effects in two unrelated mouse models.
Abstract P3033: The Pathogenic R120G Mutant Of Alpha-B-crystallin Accumulates Within Cardiac Mitochondria
Authors: Justin M Quiles, Liguo Chi, Rita H Najor, Åsa B Gustafsson
Journal: Circulation Research (2022)

Alpha-B-crystallin (CryAB) is an abundant molecular chaperone comprising nearly 5% of total cardiac mass. While predominately cytosolic, some studies note mitochondrial translocation of CryAB during stress. The autosomal dominant R120G mutation leads to CryAB misfolding and protein aggregation resulting in cardiomyopathy. Although mitochondrial dysfunction has been reported in cardiac-specific CryAB R120G transgenic mice, it is unclear whether these effects are secondary to the formation of cytotoxic aggregates or directly relate to mitochondrial damage. Using proteinase K protection assays in isolated mitochondria from mouse hearts and embryonic fibroblasts (MEFs), we have discovered that wild-type (WT) CryAB is present in the mitochondrial matrix indicating that this protein likely functions as a chaperone within the organelle. Interestingly, however, compared to the WT protein, CryAB R120G was significantly more enriched in MEF mitochondria. Furthermore, treatment of mice with adeno-associated virus serotype 9 (AAV9) encoding CryAB R120G under the control of a cardiac-specific promoter resulted in time-dependent intramitochondrial CryAB R120G accumulation across 2 and 4-weeks post injection. These data are the first to indicate that misfolded CryAB R120G resides specifically within the mitochondrial matrix. Knockdown of the mitochondrial matrix protease LonP1 significantly increased intramitochondrial as well as total CryAB R120G protein levels, and sensitized MEFs to cell death indicating that Lonp1 functions to proteolytically process imported CryAB R120G . While this response may acutely preserve mitochondrial function, sustained accumulation of intramitochondrial CryAB R120G likely exhausts proteolytic machinery within the organelle leading to induction of mitochondrial autophagy (mitophagy). Indeed, mitochondrial respiration was unchanged in both AAV9-treated and homozygous CryAB R120G knock-in mice at early time-points, whereas mitophagy-deficient Parkin -/- mice displayed significantly exacerbated mitochondrial CryAB R120G protein accumulation. Altogether, these data indicate aberrant accumulation of misfolded proteins within cardiac mitochondria underlies the pathogenicity of CryAB R120G .
Abstract GS112: An Epigenome-wide Association Study Paired With Cell-type-specific Data Identifies Key Regulators Of Heart Failure
Authors: Caitlin Lahue, Brian Gural, Abdalla Alkhawaja, Douglas Chapski, Manuel Rosa-Garrido, Eleanor Wong, Wilson Tan, Shuxun Ren, Roger Foo, Thomas M Vondriska, Yibin Wang, Christoph Rau
Journal: Circulation Research (2022)

Background: Heart Failure (HF) is driven by the interactions of multiple genetic, epigenetic, and environmental factors both within and between the cell types of the heart. Our lab uses the Hybrid Mouse Diversity Panel (HMDP), a large cohort of inbred mouse strains, to perform systems genetics analyses of isoproterenol-induced cardiac hypertrophy and failure by leveraging the benefits of a curated model organism population to identify key drivers of phenotype. We are now expanding this study into the DNA methylome, which has been convincingly linked to cardiac-associated phenotypic changes in prior studies. Methods and Results: Using Reduced Representational Bisulfite Sequencing, we profiled left ventricular tissue samples from 88 HMDP strains subjected to isoproterenol challenge (30 mg/kg/day for 21 days) and matched control animals. We identified nearly 170,000 CpGs whose methylation status varies across the HMDP and 179 significant associations (FDR of 5%) between CpG methylation and phenotypic variation using the epigenome-wide association study algorithm MACAU, including 37 associations linking CpG methylation in unchallenged hearts to 19 post-challenge phenotypes. To identify high-confidence candidate genes, we combined our loci with data from the Wellcome Trust Mouse Genomes Resource, transcriptomic and metabolomic data from the HMDP, Hi-C data, and cell-type-specific gene expression and methylation data from healthy and failing mouse hearts. We are systematically querying the resulting 78 candidates using in silico and in vitro approaches. These genes include Mospd3 , which is associated with right ventricular hypertrophy and whose knockdown in vitro results in reduced cardiomyocyte hypertrophy and changes to hypertrophy-related gene expression. Also observed were Atp9a , whose expression levels are associated with significant global DNA methylation changes between control and ISO-treated animals and whose knockdown likewise causes a reduction in observed cellular hypertrophy, and Mdga1 , whose promoter methylation status is linked to changes in 5% of expressed genes of the heart during heart failure. Further analysis and in vivo study of these loci will further our understanding of the role of DNA methylation in heart failure.
Abstract P1111: A SOX17-PDGFB Signaling Axis Regulates Aortic Root Development
Authors: Pengfei Lu, Punit Bhattachan, Megan Russell, Sonia Benkaci, Wei Cheng, Xuhui Feng, Bingruo Wu, Bin Zhou
Journal: Circulation Research (2022)

Developmental etiologies causing complex congenital aortic root abnormalities are unknown. Here we show that deletion of Sox17 in aortic root endothelium in mice causes underdeveloped aortic root leading to a bicuspid aortic valve (BAV) due to the absence of non-coronary leaflet (NCL) and mispositioned left coronary ostium (LCO). The respective defects are associated with reduced proliferation of NCL mesenchyme and aortic root smooth muscle derived from the second heart field cardiomyocytes. Mechanistically, SOX17 occupies a Pdgfb transcriptional enhancer to promote its transcription and Sox17 deletion inhibits the endothelial Pdgfb transcription and PDGFB growth signaling to the NCL mesenchyme. Restoration of PDGFB in aortic root endothelium rescues the NCL and LCO defects in Sox17 nulls. These data support a SOX17-PDGFB axis underlying aortic root development that is critical for aortic valve and coronary ostium patterning, thereby informing a potential shared disease mechanism for concurrent anomalous aortic valve and coronary arteries.
Abstract P1078: Early <i>Trypanosoma Cruzi</i> Infection Of Heart Endothelial Cells Modulates Hippo And Wnt Signaling Pathways In TSP-1 Dependent Manner
Authors: Kayla Rayford, Ayorinde Cooley, Maria Lima, Fernando Villalta, Siddharth Pratap, Pius N Nde
Journal: Circulation Research (2022)

Trypanosoma cruzi , an obligate intracellular protozoan parasite, is the etiological agent of Chagas Disease. Due to globalization, the disease is now present in all economically advanced countries of the world. About 40% of T. cruzi infected individuals will develop cardiac, neurological, and/or gastrointestinal pathology, with Chagasic Cardiomyopathy being the most prevalent pathology. During transportation, the molecular mechanisms by which the parasite signals and interact with host endothelial cells (EC), especially heart endothelium is currently unknown. Previous studies in our lab showed that the parasite dysregulates the expression of host genes, such as Thrombospondin-1 (TSP-1), to facilitate infection. Hippo and Wnt signaling pathways, in particular, have been implicated in cardiac development and disease pathogenesis. Here, we aim to evaluate the significance of TSP-1 in Hippo and Wnt signaling during the course of early T. cruzi infection. We challenged mouse heart endothelial cells (MHEC) from wild type (WT) and TSP1 knockout mice with T. cruzi and evaluated Wnt signaling by immunoblotting, YAP/β-catenin crosstalk via immunofluorescence assays, and parasite infectivity using β-catenin inhibitor. We found that in the absence of TSP1, the parasite induced the expression of Wnt-5a and enhanced the activation of GSK-3β simultaneously. In WT MHEC, the levels of Wnt-5a, p-GSK-3β were decreased compared to uninfected control. We also observed a continuous significant increase in the nuclear colocalization of β-catenin/YAP in TSP1 KO MHEC. Interestingly in WT MHEC, nuclear colocalization of β-catenin/YAP remained steady and reduced during later parasite challenge. Importantly, dysregulation of this crosstalk by pre-incubation of WT MHEC with a β-catenin inhibitor, endo-IWR 1, dramatically reduced the level of infection of WT MHEC. Parasite infectivity of inhibitor-treated WT MHEC was similar to the level of infection of TSP1 KO MHEC. These results indicate that TSP1 plays an important role in regulating Wnt/Hippo crosstalk and may be important potential therapeutic targets.
Abstract P1140: Scaling Up Engineered Cardiac Tissue For Clinical Translation As A Regenerative Therapy
Authors: Kiera Dwyer, Rajeev Kant, Kareen L Coulombe
Journal: Circulation Research (2022)

Advances in cardiovascular interventions have significantly decreased mortality due to acute myocardial infarction (MI). However, heart failure (HF) as a main sequela remains a major and devastating health burden. Globally, ~13 million people suffer from HF with systolic dysfunction and have no clinically available treatment to remuscularize their failing heart. Regenerative therapies using cardiomyocytes derived from embryonic or human-induced pluripotent stem cells (hiPSC-CMs) have emerged in large animal models and clinical trials to stabilize cardiac function post MI. Delivery of CMs through epicardially-implanted engineered cardiac tissues (ECTs) is advantageous as increased CM maturity, improved engraftment and increased mechanical support of the cardiac wall have been reported as compared to intramuscular CM injection. To date, however, the lack of rigorous studies exploring ECTs scaled to clinically relevant size (&gt;3x3cm) poses an immense hurdle to their use in clinical trials. To this end, we are focused on understanding how such ECT scale up impacts the electromechanical function of the tissue. Our work details the differentiation and proliferative expansion of hiPSC-CMs to achieve the quantity and quality of hiPSC-CMs required for clinically scaled ECTs. We fabricate ECTs by mixing hiPSC-CMs with 5% human cardiac fibroblasts in a collagen-1 hydrogel with electromechanical function assessed through optical mapping of action potential and tensile mechanical testing. We report compromised electromechanical function and structural organization of ECTs with scale up, which is ameliorated by maturation of hiPSC-CMs using drug and metabolic interventions. Because larger animals will require higher CM density in implants, we evaluated the impact of CM density on ECT formation and function. Increasing CM density (30x10 6 vs 5x10 6 hiPSC-CMs/mL) decreased ECT compaction by 70% while increasing active force generation by 5.5-fold and contractile upstroke velocity by 4.3-fold. In conclusion, we have identified the design space for fabricating ECT of clinically relevant size. By understanding the space and its functional impact, this work supports the translational feasibility of ECTs as a regenerative treatment for the failing heart.
Abstract P3114: Intermittent Fasting Potentiates Anthracycline Cardiotoxicity
Authors: Mualla Ozcan, Zhen Guo, Carla Valenzuela Ripoll, Aarti Asnani, Kenneth B Margulies, Carmen Bergom, Abhinav Diwan, Ali Javaheri
Journal: Circulation Research (2022)

Background: Anthracyclines such as doxorubicin (Dox) cause cardiotoxicity and associated autophagic impairment, though controversy exists increasing autophagy ameliorates or exacerbates Dox cardiotoxicity. Because intermittent fasting (IF), a potent stimulus of autophagy, is presently under clinical investigation in multiple human clinical trials of cancer patients receiving chemotherapy, we tested whether IF would ameliorate or exacerbate Dox cardiotoxicity in multiple murine models. Methods: Chow-fed C57BL/6 mice (n=150) were randomized to ad libitum feeding ( adlib ) or IF (every other day) and treated with vehicle or Dox (5 mg/kg IP x 4 doses). Alternatively, to stimulate autophagy and lysosomal biogenesis transcriptionally, we employed adeno-associated virus 9 (AAV9)-driven overexpression of transcription factor EB (TFEB) vs null, followed by vehicle or Dox (n=40). We further analyzed TFEB nuclear content in myocardial tissue from patients with anthracycline cardiomyopathy vs non-failing donors and patients with other non-ischemic cardiomyopathies (n=17). Results: In Dox-treated mice (but not in vehicle controls), IF significantly reduced survival (18% absolute reduction or AR) ( figure A ), left ventricular ejection fraction (LVEF) (8% AR) ( figure B ) and heart weight index (12% relative reduction) ( figure C ) compared to adlib group. Mechanistically, in Dox-treated mice, IF significantly decreased phosphorylation of mammalian target of rapamycin, increased active, nuclear TFEB content, and increased levels of the atrophy factor muscle RING-finger protein-1. In myocardial tissue from patients with anthracycline cardiomyopathy, we observed a 3.5-fold increase (p&lt;0.01) in nuclear TFEB content compared to both tissues from donors without heart failure and tissues from patients with other non-ischemic cardiomyopathies. Overexpression of TFEB exacerbated Dox-induced cardiotoxicity, including significant decreases in LVEF, left ventricular mass index, and survival. Conclusions: IF exacerbates Dox-related mortality and cardiomyopathy, likely by stimulating the autophagy-lysosomal transcriptional regulator TFEB. Our data raise concerns about the safety of IF and augmentation of TFEB activity in the context of anthracycline chemotherapy.
Abstract P3040: Mitochondrial Membrane Protein Sigmar1 Regulates Mitochondrial Ultrastructure And Respiratory Functions In The Heart
Authors: Chowdhury S Abdullah, Richa Aishwarya, Shafiul Alam, Naznin Sultana Remex, Sadia S Nitu, A. Wayne Orr, Brandon Hartman, Judy A. King, Md Shenuarin Bhuiyan
Journal: Circulation Research (2022)

Background: Sigma-1 receptor (Sigmar1) is multifunctional, ubiquitously expressed chaperone protein in mammalian cell systems. Earlier biochemical and immuno-electron microscopic analysis revealed Sigmar1’s cellular localization depends on cell and tissue systems, explaining its involvement in regulating diverse cellular and molecular functions. However, Sigmar1’s localization at organelle levels, membrane tropism, and direct molecular functions in cardiomyocytes remain elusive. Objective: We conducted systematic biochemical, microscopic, and functional assays to define Sigmar1’s subcellular localization, membrane topology, and functions in the heart. Methods and Results: Immuno-labeled quantum dots (QDs) in transmission electron microscopy revealed anti-Sigmar1 labeled QDs on the mitochondrial membranes, lysosomes, and at the sarcoplasmic reticulum-mitochondria interface. Subcellular fractionation of heart lysates also confirmed Sigmar1’s distribution in purified mitochondrial and lysosomal fractions. We further confirmed Sigmar1’s mitochondrial localization by Sigmar1’s colocalization with Mito-Tracker Red labeled isolated cardiac mitochondria. Biochemical experiments constituting alkaline extraction, detergent solubilization, and dose-dependent Proteinase K digestion on isolated heart mitochondria demonstrated Sigmar1 as an integral mitochondrial membrane protein. Sigmar1’s structural requirement for mitochondrial localization by expressing Flag-tagged Sigmar1 fragments demonstrated N-terminal required for mitochondrial localization. High-resolution mitochondrial respirometry studies showed that genetic loss of Sigmar1 in primary cardiomyocytes reduces mitochondrial respiration. Sigmar1 knock-out mice hearts also showed the accumulation of abnormal, irregular-shaped giant mitochondria and defects in mitochondrial respiration. Conclusions: Overall, our studies demonstrated that Sigmar1 is an integral mitochondrial membrane protein and is essential in maintaining mitochondrial ultrastructure and respiratory functions in the heart.
Silica and lung cancer: a controversial issue
Authors: JC Pairon, P Brochard, MC Jaurand, J Bignon
Journal: European Respiratory Journal (1991)

The role of crystalline silica in lung cancer has long been the subject of controversy. In this article, we review the main experimental and epidemiological studies dealing with this problem. Some evidence for a genotoxic potential of crystalline silica has been obtained in the rare in vitro studies published to date. In vivo studies have shown that crystalline silica is carcinogenic in the rat; the tumour types appear to vary according to the route of administration. In addition, an association between carcinogenic and fibrogenic potency has been observed in various animal species exposed to crystalline silica. An excess of lung cancer related to occupational exposure to crystalline silica is reported in many epidemiological studies, regardless of the presence of silicosis. However, most of these studies are difficult to interpret because they do not correctly take into account associated carcinogens such as tobacco smoke and other occupational carcinogens. An excess of lung cancer is generally reported in studies based on silicosis registers. Overall, experimental and human studies suggest an association between exposure to crystalline silica and an excess of pulmonary malignancies. Although the data available are not sufficient to establish a clear-cut causal relationship in humans, an association between the onset of pneumoconiosis and pulmonary malignancies is probable. In contrast, experimental observations have given rise to a pathophysiological mechanism that might account for a putative carcinogenic potency of crystalline silica.